Influence of Chiral Compounds on the Oxygen Evolution Reaction (OER) in the Water Splitting Process

Chiral Induced Spin Selectivity

Since the initial landmark study on the chiral induced spin selectivity (CISS) effect in 1999, considerable experimental and theoretical efforts have been made to understand the physical underpinnings and mechanistic features of this interesting phenomenon. As first formulated, the CISS effect refers to the innate ability of chiral materials to act as spin filters for electron transport; however, more recent experiments demonstrate that displacement currents arising from charge polarization of chiral molecules lead to spin polarization without the need for net charge flow. With its identification of a fundamental connection between chiral symmetry and electron spin in molecules and materials, CISS promises profound and ubiquitous implications for existing technologies and new approaches to answering age old questions, such as the homochiral nature of life. This review begins with a discussion of the different methods for measuring CISS and then provides a comprehensive overview of molecules and materials known to exhibit CISS-based phenomena before proceeding to identify structure-property relations and to delineate the leading theoretical models for the CISS effect. Next, it identifies some implications of CISS in physics, chemistry, and biology. The discussion ends with a critical assessment of the CISS field and some comments on its future outlook.

Chiral "doped" MOFs: an electrochemical and theoretical integrated study

This work reports on the electrochemical behaviour of Fe and Zn based metal-organic framework (MOF) compounds, which are "doped" with chiral molecules, namely: cysteine and camphor sulfonic acid. Their electrochemical behaviour was thoroughly investigated via "solid-state" electrochemical measurements, exploiting an "ad hoc" tailored experimental set-up: a paste obtained by carefully mixing the MOF with graphite powder is deposited on a glassy carbon (GC) surface. The latter serves as the working electrode (WE) in cyclic voltammetry (CV) measurements. Infrared (IR), X-ray diffraction (XRD) and absorbance (UV-Vis) techniques are exploited for a further characterization of the MOFs' structural and electronic properties. The experimental results are then compared with DFT based quantum mechanical calculations. The electronic and structural properties of the MOFs synthesized in this study depend mainly on the type of metal center, and to a minor extent on the chemical nature of the dopant.

On the Dynamics of the Carbon-Bromine Bond Dissociation in the 1-Bromo-2-Methylnaphthalene Radical Anion

This paper studies the mechanism of electrochemically induced carbon-bromine dissociation in 1-Br-2-methylnaphalene in the reduction regime. In particular, the bond dissociation of the relevant radical anion is disassembled at a molecular level, exploiting quantum mechanical calculations including steady-state, equilibrium and dissociation dynamics via dynamic reaction coordinate (DRC) calculations. DRC is a molecular-dynamic-based calculation relying on an ab initio potential surface. This is to achieve a detailed picture of the dissociation process in an elementary molecular detail. From a thermodynamic point of view, all the reaction paths examined are energetically feasible. The obtained results suggest that the carbon halogen bond dissociates following the first electron uptake follow a stepwise mechanism. Indeed, the formation of the bromide anion and an organic radical occurs. The latter reacts to form a binaphthalene intrinsically chiral dimer. This paper is respectfully dedicated to Professors Anny Jutand and Christian Amatore for their outstanding contribution in the field of electrochemical catalysis and electrosynthesis.

Chiral Induced Spin Selectivity and Its Implications for Biological Functions

Chirality in life has been preserved throughout evolution. It has been assumed that the main function of chirality is its contribution to structural properties. In the past two decades, however, it has been established that chiral molecules possess unique electronic properties. Electrons that pass through chiral molecules, or even charge displacements within a chiral molecule, do so in a manner that depends on the electron's spin and the molecule's enantiomeric form. This effect, referred to as chiral induced spin selectivity (CISS), has several important implications for the properties of biosystems. Among these implications, CISS facilitates long-range electron transfer, enhances bio-affinities and enantioselectivity, and enables efficient and selective multi-electron redox processes. In this article, we review the CISS effect and some of its manifestations in biological systems. We argue that chirality is preserved so persistently in biology not only because of its structural effect, but also because of its important function in spin polarizing electrons. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

On the Oxygen Reduction Reaction Mechanism Catalyzed by Pd Complexes on 2D Carbon. A Theoretical Study

Oxygen Reduction Reaction (ORR) is the bottle-neck strategic reaction ruling the fuel cell efficiency process. The slow kinetics of the reaction require highly effective electrocatalysts for proper boosting. In this field, composite catalysts formed by carbon nanotubes functionalized with palladium(II) complexes showed surprising catalytic activity comparable to those of a commercial Pt electrode, but the catalytic mechanisms of these materials still remain open to discussion. In this paper, we propose the combination of experimental and theoretical results to unfold the elementary reaction steps underlying the ORR catalysis.